This invention relates to information storage devices; and, more particularly, to the class of such devices, known as "charge coupled devices" (CCD's), in which mobile electric charge representing information is coupled to artificially induced potential wells in suitable storage media and is stored and translated therein by application of electric fields.
Previously disclosed forms of such apparatus, e.g., the three-phase embodiments disclosed in U.S. patent application Ser. No. 11,541, filed Feb. 16, 1970, on behalf of W. S. Boyle and G. E. Smith now abandoned and the two-phase embodiments disclosed in U.S. patent application Ser. No. 11,448, filed Feb. 16, 1970, on behalf of D. Kahng and E. H. Nicollian, now U.S. Pat. No. 3,651,349, issued Mar. 21, 1972, are operable but suffer certain disadvantageous characteristics which it is an object of this invention to alleviate.
For example, the three-phase embodiments disclosed in the aforementioned application are not amenable to serpentine data patterns without an unduly complicated interconnection pattern. Fabricating the interconnections is not an appreciable problem per se, but they do require space; and the result is an often unacceptably large area per bit of information.
The two-phase embodiments disclosed in the other application referenced above are readily amenable to serpentine data patterns but are difficult to fabricate in the form disclosed therein. Also, the built-in asymmetry in those devices forecloses the possibility of electronically reversing the direction of data transfer.